Methods and apparatus for imaging and displaying a navigable path

ABSTRACT

Various methods for imaging and navigating a selected path are described. A method of navigating a path includes the step of identifying a selected path. At least one image stream associated with navigating the selected path is identified. The displayed image stream includes visual information corresponding to traveling the selected path. In one embodiment, display of the image stream is varied in accordance with an actual location and a speed of a traveler along the selected path. Various single pass and multi-pass systems are described for capturing the visual information associated with a path. One method of acquiring visual information includes generating first and second image streams comprising visual information representing traversal of the path. Audio cues are recorded at the same plurality of locations on each pass. The audio cues permit synchronization of the image streams to locations along the path.

FIELD OF THE INVENTION

[0001] This invention relates to the field of navigational tools. Inparticular, this invention is drawn to aiding a traveler navigate apath.

BACKGROUND OF THE INVENTION

[0002] Traditional maps provide a two dimensional birdseye view ofroads, streets, and highways. Typically such maps include a limited setof geographic features such as lakes and rivers or manmade features suchas the location of a railroad or other landmarks that aid in navigation.

[0003] Navigational systems relying upon databases based on such mapsmay highlight a point-to-point path that permits the user to betterlocate the desired path within a larger map of paths. Some navigationalsystems provide the user with a series of instructions regarding thepath to be taken.

[0004] Although such navigation systems offer numerous benefits, thistype of information does not necessarily enable the user to readilyrelocate to the starting point of the selected path without additionalinformation. In addition, the textual information such as the distancebetween one point and the next point requires the user to monitor theodometer and perform computations in order to locate the next point.Thus one disadvantage of such navigational systems is that the user maynot be able to readily correlate the user's actual position with aposition on the selected path.

SUMMARY OF THE INVENTION

[0005] In view of limitations of known systems and methods, variousmethods for imaging and navigating a selected path are described.

[0006] One method of navigating a path includes the step of identifyinga selected path. At least one image stream associated with navigatingthe selected path is identified. The displayed image stream includesvisual information corresponding to traveling the selected path.

[0007] Another method of navigating a path includes the step ofidentifying a selected path. A sequence of image streams correspondingto traveling the selected path is identified. Each image stream includesvisual information associated with traversing the selected path. Thesequence of image streams is displayed in sequential order.

[0008] Another method of navigating a path includes the step ofproviding at least one image stream corresponding to a selected path.The image stream includes visual information associated with traversingthe selected path. A first position corresponding to a current positionis identified within the image stream. A second position correspondingto a desired position is identified within the image stream. The imagestream is re-positioned to the second position for display if adifference between the first and second positions exceeds apre-determined threshold. In one embodiment, the frame rate of displayof the image stream is varied in accordance with the speed of the useralong the selected path.

[0009] Various single pass and multi-pass systems are described forcapturing the visual information associated with a path. One method ofcollecting visual information for a navigable path includes the step oftraversing a network of path segments connected to nodes, wherein eachpath segment is traversed at least once. Visual information associatedwith each path segment is captured while traversing that path segment.

[0010] Another method of acquiring visual information about a navigablepath includes the step of generating a first image stream comprisingvisual information representing traversal of a path on a first pass.Audio cues are recorded at a first plurality of locations whiletraversing the path on the first pass. A second image stream comprisingvisual information representing traversal of the path on a second passis generated. Audio cues are recorded at a second plurality of locationswhile traversing the path on the second pass. The second plurality oflocations is substantially the same as the first plurality of locations.The audio cues permit synchronization of the image streams to locationsalong the path.

[0011] Other features and advantages of the present invention will beapparent from the accompanying drawings and from the detaileddescription that follows below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

[0013]FIG. 1 illustrates one embodiment of a method of selecting anddisplaying an image stream associated with navigating a selected path.

[0014]FIG. 2 illustrates one embodiment of a method of generating animage stream associated with a navigable path.

[0015]FIG. 3 illustrates a method of acquiring visual information abouta navigable path with single pass video capture systems.

[0016]FIG. 4 illustrates various types of video recorders for acquiringvisual information about a navigable path.

[0017]FIG. 5 illustrates a method of acquiring visual information abouta navigable path with multiple pass video capture systems.

[0018]FIG. 6 illustrates application of a multi-pass approach foracquiring visual information about a navigable path.

[0019]FIG. 7 illustrates one embodiment of a method of travel usingimage streams as navigational aides.

[0020]FIG. 8 illustrates one embodiment of an application of the methodof FIG. 7.

[0021]FIG. 9 illustrates one embodiment of a method of displaying animage stream associated with a selected path in accordance with anactual location and speed of travel of the user.

DETAILED DESCRIPTION

[0022] A map can be described as a plurality of nodes connected by anetwork of segments. There may be more than one route for traveling froman initial node to a destination node. A cost function can be assignedto value each possible route depending upon criteria preferred by theuser such as minimum distance, maximum speed, minimum time, maximizinghighway segments, minimizing highway segments, etc. The term “path”refers to a route comprising at least one segment or a plurality ofsequentially connected segments connecting an initial node to adestination node. A path is thus a subset of the map.

[0023] Each node can be an information node, a decision node, or both. Adecision node indicates that more than one segment can be selected fortravel at that node location. An information node may includeinformation about buildings, landmarks, etc., along the path such as gasstations, post offices, grocery stores, coffee shops, etc. or othergeographic or demographic information about the geographic area local tothe node that would be useful to a traveler. In one embodiment, aninformation node includes latitude and longitude co-ordinates for thelocation associated with the information node.

[0024] In order to aid navigation, the traveler may be provided withvisual information associated with a selected path. For example, thetraveler or user may be presented with a stream of images (i.e., imagestream) previously recorded by a prior traveler of the route. Some usersmay find the sequence of images provided by the image stream useful incorrelating their actual geographic position with their position on amap and ensuring that they are actually on their desired path.

[0025]FIG. 1 illustrates one embodiment of a method of selecting anddisplaying an image stream associated with navigating a selected path.One or more image streams illustrating navigation of one or moreassociated paths are provided in step 110. A selected path is identifiedin step 120. The image stream(s) corresponding to the selected path ispresented in step 130.

[0026] The image streams include visual information associated withtraveling the selected path. The image streams may include actualimagery captured from a prior transversal of the selected path. Theimage streams may include artistically rendered images mimicking theactual imagery. The image streams provide a traveler or user with visualcues about the path that permit travelers to confirm that they are onthe intended path and as well as their location along the selected pathduring transit. The traveler thus receives information that serves asvisual feedback for navigation.

[0027] In one embodiment, each navigable path may have a singleassociated image stream. Alternatively, a plurality of distinct imagestreams may be associated with each navigable path. The use of distinctimage streams permits, for example, selection of different views of thesame selected navigable path by selecting different streams. The viewsmay include a birdseye view of the path, an observer's view whiletraveling the path, varying levels of detail about the path, ordifferent image resolutions, for example.

[0028] The user may identify the selected path by selecting agraphically presented portion of the path. In one embodiment, the userselects a start node and a destination node which serve to identify theselected path. In some applications only the destination needs to beidentified in order to select the path. In one embodiment, the start ordestination nodes may be directly identified by their physical locations(e.g., subway) or indirectly identified through the goods or servicesassociated with the location (e.g., hospitals, universities) or otherattributes of the location (vendor location).

[0029] The image stream associated with the selected path may bepresented to the user in a number of ways. Generally, the manner ofpresentation may be dependent upon whether the device presenting theimage stream is accompanying the user during transit or not.

[0030] If the image stream(s) are displayed on a device that is nottraveling with the user (e.g., a kiosk), the user views the image streambefore traveling the path. The user is thus limited to previewing thepath to be traveled or perhaps viewing a path previously traveled, butviewing an image stream of the path while traveling is not possible.

[0031] Alternatively, the image stream may be displayed on a devicetraveling with the user such as a cellular telephone, portable digitalassistant (PDA), a vehicular navigation system, or a wireless device.This permits the user to view the image stream of the selected pathwhile traveling. The user may be provided with control of thepresentation. For example, in one embodiment the user controls theplayback speed, view (birdseye, traveling observer, resolution), zoom,pan, whether to replay, etc.

[0032] In order to provide a user with visual cues for the path to bemapped or traveled, the visual information must be acquired. A number oftechniques for acquiring the visual information are presented.

[0033] Collecting visual information for every possible path between anytwo nodes is impractical for a map of any size. Instead, sufficientvisual information is collected or generated so that a subset of thecollected visual information can be used to construct a visual pathbetween any two nodes.

[0034]FIG. 2 illustrates one embodiment of a method of capturing thevisual information. A starting node and a destination node are selectedin step 210. Visual information associated with the path is capturedwhile traveling the path between the starting and destination nodes instep 220. In one embodiment, an image stream corresponding to continuousvisual information along the path is generated in step 230.

[0035] The image stream may include panoramic (360°) views.Alternatively, an image stream consisting of a set of still imageslimited to a number of locations along the path is generated. The stillimages include easily recognizable landmarks for the user in oneembodiment.

[0036]FIG. 3 illustrates a method of acquiring visual information abouta navigable path using single pass video capture systems. In step 310,the navigable path(s) are traveled. In order to collect sufficientinformation to permit navigating any portion of the network of paths,the path between any two adjacent nodes must be traveled at least once.Once traversed, the path between adjacent nodes need not be traversedagain unless it is necessary to do so in order to ensure that the entirenetwork of paths is traversed at least once.

[0037] While traversing the network of paths, the video information iscaptured with a single pass video recorder system in step 320. Theresulting collection of video information may be indexed by node in step330. In one embodiment, the image stream is indexed by position with aco-ordinate framework such as latitude and longitude co-ordinates. Suchpositioning information may be acquired, for example, by utilizing theGlobal Positioning System (GPS) to determine latitude and longitudewhile recording the video information.

[0038]FIG. 4 illustrates a network of navigable paths 410. Examples ofsingle pass video recording systems include an omni-directional camera420, a plurality of synchronized video recorders 430, and a pair ofhemispherical cameras (e.g., bi-parabolic spherical video capture system440). System 420 records the visual information as spherical videoinformation. System 440 records the visual information as a separatevideo stream for each camera, however, the separate streams are mergedinto a composite spherical video stream. Presentation of visualinformation along a particular line of sight may require a geometrictransformation to provide a planar view.

[0039] System 430 records a separate video stream for each camera. Thestart, stop, rate, and resolution are synchronized. The captured videostreams do not collectively form an omni-directional view. Although theviews are limited to a finite number of distinct views, switching viewsmerely requires selecting a different one of the captured video streams.

[0040] As long as the entire network is captured, the particular routetaken through the network 410 by the video capture system is notcritical. Thus as long as the path 416 between any pair of adjacentnodes 412, 414 is captured at least once, the order in which the pathsare traversed is not critical. The visual information captured isintended to reflect the visually static elements of the geographic areaassociated with the map.

[0041]FIG. 5 illustrates a method of acquiring visual information abouta navigable path using a multi-pass video capture system. A single passsystem may be prohibitively expensive. As an alternative, multiplepasses with a single camera positioned to different viewing angles maybe used. Synchronization of the resulting multiple streams is necessaryto ensure that each stream indicates different viewing perspectives fromthe same point along the path at a given point in time.

[0042] In step 510, visual information associated with a selectedviewpoint is recorded while traveling a navigable path to produce animage stream. An audio cue is provided when passing pre-determinedlocations along the path in step 530. If more viewpoints are to beprovided as determined by step 540, another viewpoint is selected instep 550 for a subsequent pass. Steps 510-550 are repeated until nofurther views are needed. Instead of an audio cue, the cue is providedin the form of positional data such as longitude and latitude. Thepositional data is collected at the pre-determined locations to enablesynchronizing to the same location across image streams.

[0043] In step 560, the image streams are temporally resampled in orderto synchronize sample rates across streams. The audio cues are used tospatially synchronize the image streams with each other. If necessary,the synchronized image streams are indexed by node in step 560.

[0044]FIG. 6 illustrates application of a multi-pass approach foracquiring the visual information. Multi-pass recording system 620 ispositioned to a different viewing perspective for each pass (a)-(c)along path 610. As the recording system 620 traverses the path for agiven pass, the user provides audio cues 612-618 when encounteringspecific locations along the path 610. For each subsequent pass, theaudio cues are provided at the same point along the path. The multi-passrecording system is thus provided with audio cues that may be used tosynchronize the resulting image streams spatially with respect to thetraveled path.

[0045] Although the resulting image streams may be indexed by node forpresentation of the appropriate image stream, the recorded audio cuesmay be used as an alternative index. In effect the audio cues may serveas an alternative index for the beginning, ending, and informationalnodes.

[0046] The image stream nodes are associated with corresponding nodes ofa map so that graphical representation of the map may be associated withthe corresponding image stream associated with traveling that path. Anode may be identified by an audio cue. In the event that nodes areembodied as audio cues, speech recognition software may be used to matchup the audio cues with text contained in the map. In one embodiment, theimage stream is indexed by positioning co-ordinates such as latitude andlongitude so that the graphical representation of a map having suchinformation can be matched up with the image streams displaying thecorresponding portion of the map. The result is a graphicalrepresentation of a map comprising a plurality of nodes wherein adjacentnodes have a corresponding associated image stream.

[0047]FIG. 7 illustrates one embodiment of a method of travel usingimage streams as navigational aides. In step 710, a path is selected.Path selection may be direct such as explicit identification of thepath. Alternatively, the path selection may be derived by identifying adestination, or a starting location and a destination. If more than onepath leads to the destination, a selected path may be identified fromthe possible paths by a cost function such as distance, time, type orquality of path, etc.

[0048] In step 720, a sequence of image streams corresponding totraveling the selected path is identified. Although an image streamexists for each pair of adjacent nodes along the selected path, theimage stream may be discontinuous at one or more decision node. This isbecause the visual information between the adjacent nodes was captured,but a turn at the decision node may not have been captured. Thus mere“stitching” together of the image streams may result in significantvisual discontinuity when switching from a first image stream associatedwith approaching a decision node from one direction to a second imagestream associated with leaving the decision node in another direction.

[0049] In one embodiment, the visual discontinuities associated withdistinct image streams is handled by synthesizing turns at decisionnodes. Thus although the image streams are still presented in sequentialorder, step 730 synthesizes a turn at decision nodes between distinctimage streams, if necessary, to provide for a smoother transition.

[0050] If the source image streams are captured with omni-directionalcameras or recorded as spherical image data, the visual informationassociated with making the turn can be extracted from the source imagestream. If the image streams are collected as multiple views, the visualinformation associated with making the turn can be synthesized byswitching to different views and interpolating between views.

[0051] The image stream may be augmented with synthetic elements tofurther aid navigation. Synthetic elements include arrows to indicatedirection, annotations of landmarks (e.g., “Post Office”, “Airport”,“Grocery Store”, “Gas Station”), geographic markers (e.g., “due North”),descriptions (e.g., “sharp curve”), specific vendors (e.g., “Chevron”,“Exxon”, “McDonalds”). Synthetic elements may provide information aboutactual objects or elements recorded in the image stream, the syntheticelements themselves are not actually present along the path. Textualinstructions for traveling the selected path such as travel distancesbetween turns may be provided as synthetic elements. The contents ofinformation nodes may be presented or used to generate syntheticelements. In step 740, the selected image stream(s) are augmented withsynthetic elements.

[0052] The image streams necessarily capture the traveled path at aparticular point in time. Although landmarks, buildings, waterways,highways, etc. tend to be somewhat static in nature, other visualinformation may be somewhat dynamic in nature. Lighting, for example,varies depending upon the time of day. Features such as signage, neonlights, etc. become more prominent to the viewer at night and thus theuser tends to navigate by a different set of visual indicators. Theweather may vary unpredictably over time. Precipitation or otherconditions may contribute significantly to the appearance of thetraveled path.

[0053] Given that conditions such as time of travel (e.g., day or night)or weather may significantly affect the appearance of the path whiletraveled, accommodations may be made to account for the differences. Inone embodiment, this is accomplished by presenting image streams thatare associated with a time of travel along the selected path. Thus theselection of image streams in step 710 may be based in part on time oftravel. Storing image streams for multiple times of travel is costly interms of storage.

[0054] One alternative to storing image streams for multiple times ofday is to modify the presentation of the image streams to approximatetravel at different times of day. In step 750, the image stream ismodified using virtual elements to compensate for visual differencesbetween the recorded image stream and the path as currently traveled.

[0055] In contrast to synthetic elements that are not present inactuality, virtual elements are intended to modify the recorded imagestream to better reflect actual traveling conditions such as lighting orweather. Virtual elements are thus intended to represent or mimic visualinformation that is not captured in the recorded image stream butnonetheless exists when traveling the path at different point in time.Even if a one-to-one correspondence between virtual elements and anycorresponding element along the path does not exist, the virtualelements collectively compensate the recorded image stream to bettermatch current traveling conditions. The virtual elements mimic sceneryto accommodate for visible changes between the recorded image stream andcurrent conditions while traveling the path.

[0056] In one embodiment, an illumination correction process is appliedto the image streams to account for time of day. Illumination correctionmay include varying contrast and brightness of the image streams. In oneembodiment, illumination correction includes weighted interpolationbetween image streams captured at different times of day where theweighting is dependent upon the time of travel and the time that theimage streams were recorded. Thus the image stream is modified throughvirtual lighting to accommodate for the differences in lightingconditions between the time the image stream was acquired and the timethe traveler actually travels the path.

[0057] Virtual weather modification may be applied to accommodate fordifferences in weather conditions between the time the image stream wasacquired and the time the traveler travels the path. Thus for example,imagery for precipitation such as hail, rain, or snow may be generated.The image stream is modified with such virtual imagery in step 750 topresent the traveler with an image stream that better matches actualcurrent traveling conditions as opposed to the conditions at the timethe image stream was initially recorded. In one embodiment, weathercondition data is automatically retrieved from a broadcast source toprovide for automatic virtual compensation appropriate for actualtraveling conditions at that time.

[0058] In step 760, the image streams are displayed in sequential orderto the user with any illumination correction or synthetic elementaugmentation. In one embodiment, the image stream sequence is displayedindependent of the user's location. In an alternative embodiment,portions of the image stream sequence are displayed depending upon theuser's position on the selected path. The position of the user on theselected path may be determined, for example, by global positioningsatellite.

[0059]FIG. 8 illustrates an application of the method of FIG. 7.Navigational display 810 illustrates a graphical representation of a map820 and selected path 822. An image stream illustrating travel down theselected path from a selected viewpoint is provided in viewing area 830.Portions of the image stream are provided based in part on the actualposition 824 of the user along the selected path 822. Presentation ofthe image stream is enhanced with synthetic elements such as compassheading 832, route instructions 834 (“enter hwy on right”), and textannotations 836 (“gas station”). The complete driving instructions 840are also provided in this example. The user is given the opportunity toreview or pre-view the selected path through the use of play, rewind,and fast forward functions accessible through the menu and selectionbuttons 850. The menu and selection buttons also permit the user toselect a particular view as well as to establish preferences forpresentation of the image stream.

[0060] In kiosk applications where the display device is stationary, theuser is able to preview or review a selected path. In portableapplications, however, the use of position data may optionally be usedto control the presentation at least in part while the user is moving.

[0061] Some users may desire to have the presentation of the imagestreams controlled at least in part by their location during travel.This position feedback permits the navigation system to present theimage streams in an accurate manner related to the user's true positionrather than at an ungoverned manner such as at a fixed rate independentof the user's actual position during travel. The user may choose toenable controlling the display of the image stream(s) in accordance withposition data

[0062] In one embodiment, the navigation system has access topositioning data. The user's position may be determined, for example,from positioning data provided by the Global Positioning SatelliteSystem. GPS receivers enable users to accurately pinpoint theirlocation.

[0063]FIG. 9 illustrates an expansion of step 760 of FIG. 7incorporating position data to control at least in part the presentationof the image streams. In particular, FIG. 9 illustrates one embodimentof a method of displaying an image stream associated with a selectedpath in accordance with an actual location and speed of travel of theuser.

[0064] In step 910, the user's desired lead/lag preference isdetermined. In some embodiments, the user may prefer that the presentedimage stream reflects scenery to be encountered in a few moments orscenery passed rather than the scenery in the user's current vicinity.

[0065] In step 920, information determinative of the user's actualposition is acquired. The lead/lag preference above may represent avalue required to account for delays in acquiring the user's actualposition. In step 930, the actual position is adjusted by lead or lag toindicate the desired position. In one embodiment, the lead or lag isnonexistent so that the actual position is the desired position.

[0066] In step 940, the location within the image stream correspondingto the desired position is determined. This may be accomplished, forexample, by interpolating between information nodes containing globalposition data to determine the location within the image streamcorresponding to the desired point.

[0067] The image stream may be presented from the desired point forward.If the image stream is currently being displayed, however, suddenjumping to the desired position in the image stream may be visuallydistracting, particularly if there is a significant number of framesbetween the position of the currently displayed frame and the desiredposition within the image stream. Accordingly, step 950 determines ifthe difference between a current position and the desired positionwithin the image stream exceeds a predetermined threshold. If so, theimage stream is repositioned so that the desired position becomes thecurrent position in step 960. The process of adjusting the currentposition within the image stream(s), if necessary, is referred to asupdating. The image stream is displayed from the current location instep 970.

[0068] In one embodiment, the frame rate of the image stream is adjustedin accordance with the speed of the traveler in step 980. Suchadjustments effectively serve to prevent significant differences intraveling speed of the user versus that represented by the nominal framerate of the image stream from requiring constant repositioning of theimage stream.

[0069] The update process may be performed manually in response to arequest by the user, or continuously while the user is navigating thepath. In one embodiment, the process of acquiring position data andupdating the image stream display continues, if desired, by repeatingsteps 920-980 until the user reaches the desired destination point.

[0070] In the preceding detailed description, the invention is describedwith reference to specific exemplary embodiments thereof. Variousmodifications and changes may be made thereto without departing from thebroader spirit and scope of the invention as set forth in the claims.The specification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense.

What is claimed is:
 1. A method of navigating a path comprising thesteps of: a) identifying a selected path; b) displaying at least oneimage stream associated with navigating the selected path, wherein thedisplayed image stream includes visual information corresponding totraveling the selected path.
 2. The method of claim 1 wherein the imagestream includes actual imagery captured from a prior transversal of theselected path.
 3. The method of claim 1 wherein the image streamincludes rendered images mimicking actual imagery.
 4. The method ofclaim 1 wherein the selected path has a plurality of associated imagestreams, wherein each image stream represents travel along a portion ofthe selected path.
 5. The method of claim 1 wherein the selected pathhas a plurality of associated image streams, wherein each image streamrepresents a distinct viewpoint while traveling the selected path.
 6. Amethod of collecting visual information for a navigable path comprisingthe steps of: a) traversing a network of path segments connected tonodes, wherein each path segment is traversed at least once; and b)capturing visual information associated with each path segment whiletraversing that path segment.
 7. The method of claim 6 wherein step b)includes capturing visual information with a single pass recordingsystem.
 8. The method of claim 7 wherein the single pass recordingsystem includes at least one of an omni-directional camera, a pluralityof synchronized video recorders, and a pair of hemispherical cameras. 9.The method of claim 6 wherein step b) includes capturing visualinformation with a multi-pass recording system.
 10. A method ofacquiring visual information about a navigable path comprising the stepsof: a) generating a first image stream comprising visual informationrepresenting traversal of a path on a first pass; b) recording audiocues at a first plurality of locations while traversing the path on thefirst pass; c) generating a second image stream comprising visualinformation representing traversal of the path on a second pass; and d)recording audio cues at a second plurality of locations while traversingthe path on the second pass, wherein the second plurality of locationsis substantially the same as the first plurality of locations.
 11. Themethod of claim 10 wherein each image stream includes visual informationcorresponding to a distinct viewpoint while traversing the path.
 12. Themethod of claim 10 further comprising the step of: e) synchronizing theimage streams with each other in accordance with the audio cues.
 13. Themethod of claim 12 further comprising the step of: f) temporallyresampling the image streams to synchronize sample rate across imagestreams.
 14. The method of claim 13 wherein the path includes aplurality of path segments connected by nodes, further comprising thestep of: g) indexing the synchronized image streams by node.
 15. Amethod of navigating a path comprising the steps of: a) identifying aselected path; b) identifying a sequence of image streams correspondingto traveling the selected path, wherein each image stream includesvisual information associated with traversing the selected path; and c)displaying the sequence of image streams in sequential order.
 16. Themethod of claim 15 further comprising the step of: d) augmenting thedisplay of the sequence of image streams with synthetic elements,wherein the synthetic elements are not visually encountered whiletraversing the path.
 17. The method of claim 16 wherein the syntheticelements include at least one of a compass heading, textualinstructions, highlights, geographical information, and demographicinformation.
 18. The method of claim 15 wherein the selected pathincludes at least one decision node connecting at least three pathsegments, wherein step c) further comprises the step of synthesizing aturn at the decision node to provide a transition between sequentialimage streams.
 19. The method of claim 15 further comprising the stepof: d) applying virtual element compensation to the image streams tocompensate for differences in the image streams and actual appearance ofthe selected path.
 20. The method of claim 19 wherein step d) furthercomprising the step of applying virtual lighting compensation to theimage streams to mimic lighting conditions at a time of traveling theselected path.
 21. The method of claim 19 wherein step d) furthercomprising the step of applying virtual precipitation compensation tothe image streams to mimic weather conditions at a time of traveling theselected path.
 22. A method of navigating a path comprising the stepsof: a) providing at least one image stream corresponding to a selectedpath, wherein the image stream includes visual information associatedwith traversing the selected path; b) identifying a first positionwithin the image stream corresponding to a current position; c)identifying a second position within the image stream corresponding to adesired position; and d) re-positioning the image stream to the secondposition for display, if a difference between the first and secondpositions exceeds a pre-determined threshold.
 23. The method of claim 22wherein the pre-determined threshold is a number representing anacceptable number of image stream frames between the first and secondpositions.
 24. The method of claims 22 wherein step c) further comprisesthe step of acquiring information determinative of an actual position ofa user, wherein the desired position within the image stream correspondsto the actual position of the user.
 25. The method of claim 22 whereinstep c) further comprises the steps of: i) acquiring informationdeterminative of an actual position of a user and a corresponding actualposition within the image stream; and ii) calculating the desiredposition as an offset to the actual position within the image streamsuch that the desired and actual positions within the image stream aredistinct.
 26. The method of claim 22 further comprising the step of: e)varying a frame rate of display of the image stream in accordance with aspeed of travel of a user along the selected path.